Phenylalanine

Phenylalanine, often sold as L-phenylalanine or DL-phenylalanine, is an essential amino acid that is normally converted to tyrosine.

Theory

McGregor (2019) found that in people with ME/CFS, the 7-day severity of post-exertional malaise (PEM) and the 12-month frequency of PEM scores correlated with blood glucose levels, and negatively correlated with hypoxanthine, phenylalanine, lactate and threonine.

Risks and safety

Phenylalanine is generally recognized as safe, except for people with phenylketonuria (PKU), a genetic disorder that prevents the metabolism of phenylalanine. Phenylalanine is found in many different foods.

Costs and availability

Inexpensive and available over the counter as a nutritional supplement.

Notable studies

• 2016, Metabolic profiling indicates impaired pyruvate dehydrogenase function in myalgic encephalopathy/chronic fatigue syndrome (Full Text)
• 1977, DL-phenylalanine in depressed patients: An open study (Abstract)
• 2019, Post-exertional malaise is associated with hypermetabolism, hypoacetylation and purine metabolism deregulation in ME/CFS cases - (Full text)

See also

• Tyrosine
• Depression

Learn more

• L-Phenylalanine - DrugBank Online
• L-Phenylalanine - PubChem

post-exertional malaise (PEM) - A notable exacerbation of symptoms brought on by small physical or cognitive exertions. PEM may be referred to as a "crash" or "collapse" and can last for days or weeks. Symptoms can include cognitive impairments, muscle pain, trouble remaining upright (orthostatic intolerance), sleep abnormalities, and gastro-intestinal impairments, and others.

See post-exertional malaise.

An alternate term that is sometimes used for myalgic encephalomyelitis, by people who believe the evidence for inflammation in ME is insufficient. This terminology reflects the belief that the "-itis" suffix implies inflammation.

myalgic encephalopathy An alternate term that is sometimes used for myalgic encephalomyelitis, by people who believe the evidence for inflammation in ME is insufficient. This terminology reflects the belief that the "-itis" suffix implies inflammation.

myalgic encephalomyelitis (M.E.) - A disease often marked by neurological symptoms, but fatigue is sometimes a symptom as well. Some diagnostic criteria distinguish it from chronic fatigue syndrome, while other diagnostic criteria consider it to be a synonym for chronic fatigue syndrome. A defining characteristic of ME is post-exertional malaise (PEM), or post-exertional neuroimmune exhaustion (PENE), which is a notable exacerbation of symptoms brought on by small exertions. PEM can last for days or weeks. Symptoms can include cognitive impairments, muscle pain (myalgia), trouble remaining upright (orthostatic intolerance), sleep abnormalities, and gastro-intestinal impairments, among others. An estimated 25% of those suffering from ME are housebound or bedbound. The World Health Organization (WHO) classifies ME as a neurological disease.

post-exertional malaise (PEM) - A notable exacerbation of symptoms brought on by small physical or cognitive exertions. PEM may be referred to as a "crash" or "collapse" and can last for days or weeks. Symptoms can include cognitive impairments, muscle pain, trouble remaining upright (orthostatic intolerance), sleep abnormalities, and gastro-intestinal impairments, and others.

See myalgic encephalomyelitis.

See chronic fatigue syndrome.